Remove the rose hips once ripe. The rose hips will start out small and green, then change color as they grow until they are completely red, orange, brown, or purple. You may pick them at this point, or wait until they are just beginning to dry out and wrinkle. Don't wait until they are fully dry and brown, as the seeds inside may have died by this point.
Plant the rose cuttings at any point throughout the year. Some people like to plant them during the cool months, while others wait until the early summer. Rose cuttings should be able to grow during any season. However, keep in mind that they'll need to be constantly watered, so if you plant them during the summer or live in a hot climate, they're going to dry out faster. For this reason, the rainy season might be your best option.
Plant the seeds. Some store-bought seeds can be planted immediately. If you germinated your own seeds as described above, plant them as soon as they begin to sprout. Plant with the sprout pointed downward, as this is the root. Lightly cover them with soil, about 1/4 inch (6 mm) deep. Space seeds at least 2 inches (5 cm) apart to minimize competition.
Select two roses that you want to cross-pollenate. The blooms should not be too tight, perhaps about one-half to 3/4 open. Carefully peel off all the petals. The rose stamens inside should look golden yellow and fresh. With sterile tweezers or cuticle scissors, carefully remove all the stamens at the base of the rose hip, so you do not damage the pollen sacs (anthers). Place the rose stamens into separate, clean film canisters, and place the canisters in a dry place, but not in direct sunlight.
A gentle way to clean the rose seeds is to use a Cuisinart or other brand of blender with a dough blending attachment, which is made of plastic and does not have sharp blades. You can blend the rose seeds using this gentle dough attachment for several minutes without any damage to the seeds. Do not use a blender with sharp metal blades as damage to the rose seeds may occur.
Remove the seeds from the fridge. Try to do this around the time that the seeds would normally start to germinate, such as in early spring. Make sure that the environment outside of the fridge is about 70 degrees Fahrenheit. The seed will not sprout until you take them out of the fridge. Depending on the rose variety and individual seeds, the seeds could take anywhere from four to sixteen weeks to germinate. Often, 70% or more of the seeds never sprout at all.
Cover the cutting loosely, pot and all, with a plastic bag or plastic wrap and keep the soil moist. Putting a tall stake into the pot will hold the plastic away from the leaves. If the plastic touches the leaves, they remain wet and can succumb to a fungus disease. Along the same lines, make sure the condensation can escape from the plastic or the stem will rot.